Air conditioner and method for controlling an air conditioner

ABSTRACT

An air conditioner and a method for controlling an air conditioner are provided. The air conditioner may include at least one indoor device; an electric heat pump (EHP) outdoor device connected to the at least one indoor device, configured to drive a first compressor using electric power, and having a first outdoor heat exchanger for heat exchange with a refrigerant; a gas heat pump (GHP) outdoor device connected in parallel with the EHP outdoor device, connected to the at least one indoor device, and having an engine configured to drive a second compressor using a burned gas, a second outdoor heat exchanger for heat exchange with the refrigerant, and a waste heat exchanger configured to exchange heat with the refrigerant using waste heat of the engine; and a controller configured to control a warming operation or a defrosting operation of the EHP outdoor device and the GHP outdoor device, and to supply a high pressure refrigerant from the second compressor of the GHP outdoor device to the EHP outdoor device while the EHP outdoor device performs the defrosting operation.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority under 35 U.S.C. §119 to KoreanApplication No. 10-2015-0004275, filed in Korea on Jan. 12, 2015, whoseentire disclosure is hereby incorporated by reference.

BACKGROUND

1. Field

An air conditioner and a method for controlling an air conditioner aredisclosed herein.

2. Background

An air conditioner is an apparatus that cools, warms, or purifies indoorair to provide a more comfortable indoor environment for a user. An airconditioner may be classified as an electric heat pump (EHP) type, whichuses electric power or a gas heat pump (GHP) type, which uses a gasfuel, such as liquid petroleum gas (LPG) and liquefied natural gas(LNG), according to a power source for driving a compressor. In a GHPtype, an engine is operated by burning a gas fuel, and thus, acompressor is driven.

A conventional EHP type air conditioner is disclosed in Korean PatentApplication No. 10-2003-0077857, which is hereby incorporated byreference. Such a conventional air conditioner includes a single outdoorunit or device or a combination of a plurality of outdoor units ordevices. In the conventional air conditioner in which a plurality of EHPtype outdoor units are combined, when an outdoor heat exchanger iscovered with frost due to freezing, for example, a warming operation isstopped, and a defrosting operation is performed. Therefore, in theconventional air conditioner, there is a problem in that the warmingoperation is stopped while the defrosting operation is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described in detail with reference to the followingdrawings in which like reference numerals refer to like elements, andwherein:

FIG. 1 is a schematic diagram of an air conditioner according to anembodiment;

FIG. 2 is a schematic diagram illustrating an operation of the airconditioner of FIG. 1;

FIG. 3 is a graph Illustrating a two-stage compression cycle of the airconditioner of FIG. 1;

FIG. 4 is a graph Illustrating a continuous warming operation of the airconditioner of FIG. 1; and

FIG. 5 is a flowchart of a method for controlling an air conditioneraccording to an embodiment.

DETAILED DESCRIPTION

In the following detailed description of embodiments, reference is madeto the accompanying drawings that form a part hereof, and in which isshown by way of illustration embodiments which may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the embodiments, and it is understood that otherembodiments may be utilized and that logical structural, mechanical,electrical, and chemical changes may be made without departing from thespirit or scope. To avoid detail not necessary to enable those skilledin the art to practice the embodiments, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope is defined only by the appended claims.

FIG. 1 is a schematic diagram of an air conditioner according to anembodiment. Referring to FIG. 1, the air conditioner 1 may include anindoor unit or device 10 and an outdoor unit or device 100. One or aplurality of indoor units 10 may be provided. The one or more indoorunits 10 may be connected with the outdoor unit 100, and may cool, warm,or purify indoor air.

The indoor unit 10 may include a pair of indoor unit pipes 12 and 14 forconnection with the outdoor unit 100. The pair of indoor unit pipes 12and 14 may include a first indoor unit pipe 12 that connects an EHPoutdoor unit or device 200 and a GHP outdoor unit or device 300, whichwill be described hereinafter, and a second indoor unit pipe 14 thatconnects the EHP outdoor unit 200 and the GHP outdoor unit 300, whichwill be described hereinafter.

The outdoor unit 100 may be connected with the one or more indoor unit10, and may perform compressing and expanding, for example, of arefrigerant to allow a sufficient heat exchanging operation of theindoor unit 10. A plurality of outdoor units 100 may be provided.Hereinafter, as an example, an embodiment having one pair of outdoorunits 100 will be described.

The outdoor unit 100 may be a combined type including an electric heatpump (EHP) type using electric power and a gas heat pump (GHP) typeusing a gas fuel, such as LPG and LNG. The outdoor unit 100 may includea first connection valve 110, a second connection valve 120, the EHPoutdoor unit 200, the GHP outdoor unit 300, and a controller 500. Thefirst connection valve 110 may be connected with the first indoor unitpipe 12 of the indoor unit 10 to transfer a high pressure refrigerantfrom the outdoor unit 100 to the indoor unit 10 in a warming operation.The second connection valve 120 may be connected with the second indoorunit pipe 14 of the indoor unit 10 to transfer a low pressurerefrigerant from the indoor unit 10 to the outdoor unit 100 in thewarming operation.

The EHP outdoor unit 200 may be an outdoor unit operated using an EHPmethod, and may include a first compressor 210, a first accumulator 220,a first outdoor heat exchanger 250, a temperature sensor 255, a firstoutdoor heat exchanger control valve 260, and a first four-way valve270. The first compressor 210 may compress the refrigerant, and may bedriven by applying a voltage. When the voltage is applied to the firstcompressor 210, the first compressor 210 may compress the refrigerant.

The first accumulator 220 may supply the refrigerant to the firstcompressor 210. When the refrigerant flows backward or is introducedinto the first compressor 210 as a liquid, the first compressor 210 maybe damaged, and thus, the first accumulator 220 may temporarily store amixture of oil and the refrigerant.

The first outdoor heat exchanger 250 may evaporate or condense therefrigerant according to a cooling operation or a warming operations ofthe air conditioner 1. When the air conditioner 1 performs the coolingoperation, the refrigerant may be condensed, and when the airconditioner 1 performs the warming operation, the refrigerant may beevaporated.

The temperature sensor 255 may detect a temperature of the first outdoorheat exchanger 250. The temperature sensor 255 may be provided at or inthe first outdoor heat exchanger 250. The temperature sensor 255 may beone of various temperature sensors that detect a temperature. The firstoutdoor heat exchanger control valve 260 may control a flow of therefrigerant to the first outdoor heat exchanger 250. As the firstoutdoor heat exchanger control valve 260 is well known, detaileddescription thereof has been omitted.

The first four-way valve 270 may switch a passage of the refrigerantflowing in the EHP outdoor unit 200. According to on/off of electricpower, the first four-way valve 270 may be switched to an EHP warmingmode, in which the indoor unit 10 may be connected with the firstcompressor 210 when the EHP outdoor unit 200 performs the warmingoperation, and an EHP defrosting mode or an EHP cooling mode, in whichthe first compressor 210 may be connected with the second compressor 310of the GHP outdoor unit 300, which will be described hereinafter, whenthe EHP outdoor unit 200 performs the defrosting operation. Morespecifically, the first four-way valve 270 may be switched to the EHPwarming mode when the electric power is supplied, and may be switched tothe EHP defrosting mode or the EHP warning mode when the electric poweris not supplied.

The GHP outdoor unit 300 may be an outdoor unit operated using a GHPmethod, and may include a second compressor 310, a second accumulator320, an engine 330, a cooling water heat exchanger 340, a cooling waterpump 345, a second outdoor heat exchanger 350, a second outdoor heatexchanger control valve 355, a waste heat exchanger 370, a waste heatexchanger control valve 375, and a second four-way valve 380. The secondcompressor 310 may compress the refrigerant, and may be operated throughdriving of the engine 330, which will be described hereinafter. When adriving force is transmitted to the second compressor 310 by the engine330, the second compressor 310 may compress the refrigerant, similar tothe first compressor 210.

The second accumulator 320 may supply the refrigerant to the secondcompressor 310. When the refrigerant flows backwards or is introducedinto the second compressor 310 as a liquid, the second compressor 310may be damaged, and thus, the second accumulator 320 may temporarilystore the mixture of oil and the refrigerant, similar to the firstaccumulator 220. The engine 330 may transmit the driving force to thesecond compressor 310, and may be operated by burning of the gas fuel,such as LPG and LNG. The GHP outdoor unit 300 may be operated using theGHP method using the burned gas from the engine 330.

The cooling water heat exchanger 340 may cool the engine 330. Thecooling water heat exchanger 340 may absorb heat of the engine 330overheated by driving of the engine 330 using cooling water. The coolingwater pump 345 may provide a flowing force to the cooling water, and maybe connected with the cooling water heat exchanger 340. As the coolingwater pump 345 is well known, detailed description thereof has beenomitted.

The second outdoor heat exchanger 350 may evaporate or condense therefrigerant through the cooling and warming operations of the airconditioner 1, similar to the first outdoor heat exchanger 250. When theair conditioner 1 performs the cooling operation, the refrigerant may becondensed, and when the air conditioner 1 performs the warmingoperation, the refrigerant may be evaporated.

The second outdoor heat exchanger control valve 355 may control the flowof the refrigerant to the second outdoor heat exchanger 350. The secondoutdoor heat exchanger control valve 355 may be opened when the EHPoutdoor unit 200 performs the warming operation, and may be closed whenthe EHP outdoor unit 200 performs the defrosting operation or thecooling operation. The waste heat exchanger 370 may evaporate orcondense the refrigerant through the cooling and warming operations ofthe air conditioner 1, similar to the second outdoor heat exchanger 350.The waste heat exchanger 370 may be a plate type heat exchanger. Thewaste heat exchanger 370 may evaporate or condense the refrigeranttogether with the second outdoor heat exchanger 350.

The waste heat exchanger control valve 375 may control the flow ofrefrigerant to the waste heat exchanger 370. As the waste heat exchangercontrol valve 375 is well known, detailed description thereof has beenomitted. The second four-way valve 380 may switch a passage of therefrigerant flowing in the GHP outdoor unit 300. Similar to the firstfour-way valve 270, the second four-way valve 380 may be switched to aGHP warming mode when the electric power is supplied, and may beswitched to a GHP cooling mode when the electric power is not supplied.

The controller 500 may control an overall operation of the outdoor unit100, such as the cooling operation, the warming operation, and thedefrosting operation of the EHP outdoor unit 200 and the GHP outdoorunit 300. For example, when the EHP outdoor unit 200 performs thedefrosting operation, the controller 500 may control the high pressurerefrigerant from the second compressor 310 of the GHP outdoor unit 300to be supplied to the EHP outdoor unit 200.

The controller 500 may perform the defrosting operation of the EHPoutdoor unit 200 at a predetermined frosting temperature difference. Atemperature difference between an external air temperature and atemperature of the first outdoor heat exchanger 250 may be set as thepredetermined frosting temperature difference. The controller 500 mayperform the defrosting operation of the EHP outdoor unit 200 when thepredetermined frosting temperature difference exceeds about 15° C. Thisis only an example, and the predetermined frosting temperature may bechanged properly according to design.

During the warming operation of the EHP outdoor unit 200 and the GHPoutdoor unit 300, when frosting of the first outdoor heat exchanger 250of the EHP outdoor unit 200 is detected, the controller 500 may switchthe warming operation of the EHP outdoor unit 200 to the defrostingoperation thereof. During the defrosting operation of EHP outdoor unit200, the controller 500 may switch an operation mode of the firstfour-way valve 270 to the EHP defrosting mode, and may connect the firstcompressor 210 with the second compressor 310. The switching of thefirst four-way valve 270 may be performed according to on/off of theelectric power supplied to the first four-way valve 270. Further, in thedefrosting operation of the EHP outdoor unit 200, the controller 500 mayclose the second outdoor heat exchanger control valve 355, and open thewaste heat exchanger control valve 375.

When a predetermined defrosting completion temperature is reached, thecontroller 500 may switch the defrosting operation of the EHP outdoorunit 200 to the warming operation thereof. The temperature of the firstoutdoor heat exchanger 250 may be set as the predetermined defrostingcompletion temperature. The controller 500 may switch the defrostingoperation of the EHP outdoor unit 200 to the warming operation when thepredetermined defrosting completion temperature is about 10° C. or more.This is only an example, and the predetermined defrosting completiontemperature may be changed properly according to design.

As described above, the controller 500 may control the overall operationof the outdoor unit 100 of the air conditioner 1. Hereinafter, anoperation of the air conditioner 1 according to an embodiment will bedescribed.

FIG. 2 is a schematic diagram illustrating an operation of the airconditioner of FIG. 1. FIG. 3 is a graph illustrating a two-stagecompression cycle of the air conditioner of FIG. 1. FIG. 4 is a graphillustrating a continuous warming operation of the air conditioner ofFIG. 1.

Referring to FIGS. 2 to 4, during the warming operation of the airconditioner 1, when frosting of the first outdoor heat exchanger 250 ofthe EHP outdoor unit 200 due to freezing, for example, is detected, thecontroller 500 may switch the operation of EHP outdoor unit 200 to thedefrosting operation. A frosting detecting temperature difference may bedesigned as, for example, the above-described temperature difference atwhich the temperature difference between the external air temperatureand the temperature of the first outdoor heat exchanger 250 exceedsabout 15° C. The temperature of the first outdoor heat exchanger 250 maybe detected by the temperature sensor 255.

In the defrosting operation of the EHP outdoor unit 200, the controller500 may cut off the electric power supply to the first four-way valve270, and may control the first four-way valve 270 to connect the firstoutdoor heat exchanger 250 with the second outdoor heat exchanger 350.The controller 500 may control the GHP outdoor unit 300 to continuouslyperform the warming operation, close the second outdoor heat exchangercontrol valve 355 of the second outdoor heat exchanger 350, and open thewaste heat exchanger control valve 375. As described above, the openingand closing of the second outdoor heat exchanger control valve 355 andthe waste heat exchanger control valve 375 may be performedautomatically.

The flow of the refrigerant may be as follows. The refrigerantcompressed by and flowing from the second compressor 310 of the GHPoutdoor unit 300 may be branched to the first indoor unit pipe 12 of theindoor unit 10 and the EHP outdoor unit 200 through the second four-wayvalve 380. The refrigerant branched to the EHP outdoor unit 200 may flowinto the first four-way valve 270, the first accumulator 220, and thefirst compressor 210. The refrigerant flowing into the first compressor210 may be compressed again by the first compressor 210, and then mayflow to the first outdoor heat exchanger 250 through the first four-wayvalve 270.

That is, as illustrated in FIG. 3, the refrigerant may be compressed intwo stages. The refrigerant compressed in two stages may pass throughthe first outdoor heat exchanger 250, and then may be introduced intothe GHP outdoor unit 300. The temperature of the first outdoor heatexchanger 250 may be reduced due to the passing of the refrigeranttherethrough. The refrigerant introduced into the GHP outdoor unit 300may then be introduced again into the second compressor 310 via theopened waste heat exchanger control valve 375, the waste heat exchanger370, and the second accumulator 320. The refrigerant introduced into thesecond compressor 310 may be supplied to the indoor unit 10 and the EHPoutdoor unit 200, as previously described, and thus may form acirculation cycle.

When the refrigerant is primarily compressed to a predetermined targethigh pressure completing the defrosting of the first outdoor heatexchanger 250, the controller 500 may control a rotating speed of thesecond compressor 310. That is, the controller 500 may increase orreduce the rotating speed of the second compressor 310 until therefrigerant reaches the predetermined target high pressure. Thepredetermined target high pressure may be about 2900 kPa. This is onlyan example, and the predetermined target high pressure may be properlychanged according to design.

When the refrigerant is secondarily compressed, the controller 500 mayincrease the rotating speed of the first compressor 310. That is, thecontrol unit 500 may increase the rotating speed of the first compressor310 to complete the defrosting of the first outdoor heat exchanger 250when the refrigerant is secondarily compressed. When the refrigerantreaches a defrosting temperature of the first outdoor heat exchanger 250through the circulation circle, the controller 500 may again switch thedefrosting operation of the EHP outdoor unit 200 to the warmingoperation thereof. The defrosting completion temperature may be atemperature at which the temperature of the first outdoor heat exchanger250 is about 10° C. or more. This is only an example, and thetemperature may be changed properly according to design.

When the EHP outdoor unit 200 is switched to the warming operation, thecontroller 500 may turn on the electric power supply to the firstfour-way valve 270, and control the first four-way valve 270 to connectthe first compressor 210 to the indoor unit 10. Then, the outdoor unit100 of the air conditioner 1, that is, both of the EHP outdoor unit 200and the GHP outdoor unit 300 may perform the warming operation.

As described above, in the air conditioner 1 according to an embodiment,when the EHP outdoor unit 200 performs the defrosting operation, the GHPoutdoor unit 300 may continuously perform the warming operation throughthe waste heat exchanger 370 using the waste heat of the engine 330. Inthe case of the GHP outdoor unit 300, even though the second outdoorheat exchanger 350 may be covered with frost, the defrosting operationmay not be required due to the waste heat exchanger 370 using the wasteheat of the engine 330. Thus, in the air conditioner 1 according to anembodiment, as illustrated in FIG. 4, even when the EHP outdoor unit 200performs the defrosting operation, the warming operation may becontinuously performed, and thus, the problem in which the warmingoperation may be stopped due to the defrosting operation may not occur.

As such, in the air conditioner 1 according to an embodiment, even whenthe outdoor heat exchanger is covered with frost due to freezing whilethe warming operation is performed, the warming operation may becontinuously performed through the GHP outdoor unit 300 provided at afirst stage side of a two-stage compression cycle, and thus, warmingefficiency may be remarkably enhanced. Further, in the air conditioner 1according to an embodiment, the two-stage compression cycle may beformed when the EHP outdoor unit 200 performs the defrosting operation,and the EHP outdoor unit 200 side may serve as a high stage side cycle,and thus, a defrosting time may be also reduced.

Hereinafter, a method for controlling an air conditioner according to anembodiment will be described.

FIG. 5 is a flowchart of a method for controlling an air conditioneraccording to an embodiment. Referring to FIG. 5, when a warmingoperation is performed, the air conditioner, such as air conditioner ofFIG. 1, may switch on a first four-way valve of an EHP outdoor unit,such as first-four way valve 270 of EHP outdoor unit 200 of FIG. 1, anda second four-way valve of a GHP outdoor unit, such as second four-wayvalve 380 of EHP outdoor unit 300 of FIG. 1, so that both of the EHPoutdoor unit and the GHP outdoor unit may be performed in the warmingmode (S10).

Then, the air conditioner may determine whether a first outdoor heatexchanger, such as first outdoor heat exchanger 250 of FIG. 1, iscovered with frost (S20). Whether the first outdoor heat exchanger iscovered with frost is determined using a difference between an externalair temperature and a temperature of the first outdoor heat exchanger.When the temperature difference between the external air temperature andthe temperature of the first outdoor heat exchanger exceeds about 15°C., it may be determined that the first outdoor heat exchanger iscovered with the frost.

The air conditioner may switch off the first four-way valve of the EHPoutdoor unit and control the EHP outdoor unit to operate in a defrostingmode upon determining that the first outdoor heat exchanger is coveredwith frost. In a case of the GHP outdoor unit, the air conditioner maymaintain a state in which the second four-way valve may be switched on,and thus, allow the GHP outdoor unit to continuously operate in an EHPwarming mode (S30). The air conditioner may continuously switch on thefirst four-way valve of the EHP outdoor unit and the second four-wayvalve of the GHP outdoor unit and continuously perform the warmingoperation (S60) upon determining that the first outdoor heat exchanger,such as first outdoor heat exchanger is not covered with the frost.

The air conditioner may control a rotating speed of compressors of anoutdoor unit, such as first and second compressors 210, 310 of outdoorunit 100 of FIG. 1, after the EHP outdoor unit is switched to an EHPdefrosting mode. More specifically, the air conditioner may control arotating speed of the second compressor and an increase in the rotatingspeed of a first compressor until it reaches a target high pressure(S40). As previously described, in an embodiment, the two-stagecompression cycle may be formed through this process.

The air conditioner may determine whether defrosting of the EHP outdoorunit is completed through the two-stage cycle operation (S50). Whetherthe defrosting of the EHP outdoor unit is completed may be determinedbased on whether the first outdoor heat exchanger reaches thepredetermined temperature. In one embodiment, when the temperature ofthe first outdoor heat exchanger exceeds about 10° C., it may bedetermined that the defrosting of the EHP outdoor unit is completed.

The air conditioner may switch on the first four-way valve again, andswitch the EHP outdoor unit to be operated in the EHP warming mode whenit is determined that the defrosting of the EHP outdoor unit iscompleted. In a case of the GHP outdoor unit, the air conditioner maycontinuously maintain a state in which the second four-way valve isswitched on (S60). When it is determined that the defrosting of the EHPoutdoor unit is not completed, the air conditioner may control therotating speed of the compressors (S50).

As described above, when the EHP outdoor unit performs the defrostingoperation, the air conditioner according to an embodiment maycontinuously perform the warming operation, and may also remarkablyreduce a defrosting operation time of the EHP outdoor unit using wasteheat of the GHP outdoor unit.

An air conditioner capable of solving the above-described problem, and amethod for controlling an air conditioner is provided according toembodiments disclosed herein.

Embodiments disclosed herein provide an air conditioner that may includeat least one indoor unit or device; an EHP outdoor unit or deviceconnected to the at least one indoor unit, configured to drive a firstcompressor using electric power, and having a first outdoor heatexchanger that performs heat exchange with a refrigerant; a GHP outdoorunit or device connected in parallel with the EHP outdoor unit,connected to the at least one indoor unit, and having an engineconfigured to drive a second compressor through a burned gas, a secondoutdoor heat exchanger that performs heat exchange with the refrigerant,and a waste heat exchanger configured to exchange heat with therefrigerant using waste heat of the engine; and a controller configuredto control a warming operation or a defrosting operation of the EHPoutdoor unit and the GHP outdoor unit, and to supply a high pressurerefrigerant from the second compressor of the GHP outdoor unit to theEHP outdoor unit while the EHP outdoor unit performs the defrostingoperation.

The controller may switch the EHP outdoor unit to perform the defrostingoperation when it is detected that the first outdoor heat exchanger ofthe EHP outdoor unit is covered with frost while the EHP outdoor unitand the GHP outdoor unit perform the warming operation. The EHP outdoorunit may include a first four-way valve, which may be switched to an EHPwarming mode, which connects the first compressor with the at least oneindoor unit when the EHP outdoor unit performs the warming operation,and is converted to an EHP defrosting mode, which connects the firstcompressor with the second compressor of the GHP outdoor unit, when theEHP outdoor unit performs the defrosting operation. When the EHP outdoorunit performs the defrosting operation, the controller may switch thefirst four-way valve to the EHP defrosting mode, and may supply highpressure refrigerant of the second compressor to the first compressor.

The GHP outdoor unit may include a second outdoor heat exchanger controlvalve configured to control a flow of the refrigerant flowing into thesecond outdoor heat exchanger, and a waste heat exchanger control valveconfigured to control a flow of the refrigerant flowing into the wasteheat exchanger. When the EHP outdoor unit performs the defrostingoperation, the controller may close the second outdoor heat exchangercontrol valve, and may open the waste heat exchanger control valve.

A temperature sensor configured to detect a temperature of the firstoutdoor heat exchanger may be provided at the first outdoor heatexchanger. The controller may perform the defrosting operation of theEHP outdoor unit at a predetermined frosting temperature, and may switchthe defrosting operation of the EHP outdoor unit to a warming operationthereof at a predetermined defrosting completion temperature. Thepredetermined frosting temperature may be a temperature at which atemperature difference between an external air temperature and atemperature of the first outdoor heat exchanger exceeds about 15° C. Thepredetermined defrosting completion temperature may be a temperature atwhich the temperature of the first outdoor heat exchanger is about 10°C. or more.

Embodiments disclosed herein further provide a control method of an airconditioner that may include at least one indoor unit or device, an EHPoutdoor unit or device connected to the at least one indoor unit andconfigured to drive a first compressor using electric power, and a GHPoutdoor unit or device connected in parallel with the EHP outdoor unit,connected to the at least one indoor unit and having an engine usedthrough a burned gas. The control method may include performing awarming operation of the EHP outdoor unit and the GHP outdoor unit;switching the EHP outdoor unit to perform a defrosting operation whenthe EHP outdoor unit reaches a predetermined frosting temperature; andsupplying a high pressure refrigerant of the GHP outdoor unit to the EHPoutdoor unit. In the supplying of the high pressure refrigerant of theGHP outdoor unit to the EHP outdoor unit, a two-stage compression cyclein which the high pressure refrigerant of the GHP outdoor unit iscompressed by the compressor of the GHP outdoor unit and then compressedby the compressor of the EHP outdoor unit may be formed.

The control method may include switching the EHP outdoor unit to performa warming operation when the EHP outdoor unit reaches a predetermineddefrosting completion temperature. The predetermined frostingtemperature may be a temperature at which a temperature differencebetween an external air temperature and a temperature of the firstoutdoor heat exchanger exceeds about 15° C. The predetermined defrostingcompletion temperature may be a temperature at which the temperature ofthe first outdoor heat exchanger is about 10° C. or more.

According to embodiments disclosed herein, when the EHP outdoor unitperforms the defrosting operation, the warming operation may becontinuously performed, and also the defrosting operation time of theEHP outdoor unit may be remarkably reduced using the waste heat of theGHP outdoor unit.

Even though all elements of embodiments may be coupled into one oroperated in the combined state, embodiments are not limited to suchembodiments. That is, all the elements may be selectively combined witheach other without departing the scope. Further, when it is describedthat one comprises (or comprises or has) some elements, it should beunderstood that it may comprise (or include or have) only thoseelements, or it may comprise (or include or have) other elements as wellas those elements if there is no specific limitation. Unless otherwisespecifically defined herein, all terms comprising technical orscientific terms are to be given meanings understood by those skilled inthe art. Like terms defined in dictionaries, generally used terms needsto be construed as meaning used in technical contexts and are notconstrued as ideal or excessively formal meanings unless otherwiseclearly defined herein.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment. The appearances ofsuch phrases in various places in the specification are not necessarilyall referring to the same embodiment. Further, when a particularfeature, structure, or characteristic is described in connection withany embodiment, it is submitted that it is within the purview of oneskilled in the art to effect such feature, structure, or characteristicin connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. An air conditioner, comprising: at least oneindoor device; an electric heat pump (EHP) outdoor device connected tothe at least one indoor device, configured to drive a first compressorusing electric power, and having a first outdoor heat exchanger thatperforms heat exchange with a refrigerant; a gas heat pump (GHP) outdoordevice connected in parallel with the EHP outdoor device, connected tothe at least one indoor device, and including an engine configured todrive a second compressor using a burned gas, a second outdoor heatexchanger that performs heat exchange with the refrigerant, and a wasteheat exchanger configured to exchange heat with the refrigerant usingwaste heat of the engine; and a controller configured to control awarming operation or a defrosting operation of the EHP outdoor deviceand the GHP outdoor device, and to supply a high pressure refrigerantfrom the second compressor of the GHP outdoor device to the EHP outdoordevice while the EHP outdoor device performs the defrosting operation.2. The air conditioner according to claim 1, wherein the controllerswitches the EHP outdoor device to perform the defrosting operation whenit is determined that the first outdoor heat exchanger of the EHPoutdoor device is covered with frost while the EHP outdoor device andthe GHP outdoor device perform the warming operation.
 3. The airconditioner according to claim 2, wherein the EHP outdoor deviceincludes a first four-way valve, which is switched to an EHP warmingmode during which the first compressor is connected with the at leastone indoor device when the EHP outdoor device performs the warmingoperation, and which is switched to an EHP defrosting mode during whichthe first compressor is connected with the second compressor when theEHP outdoor device performs the defrosting operation.
 4. The airconditioner according to claim 3, wherein when the EHP outdoor deviceperforms the defrosting operation, the controller switches the firstfour-way valve to the EHP defrosting mode, and supplies the highpressure refrigerant of the second compressor to the first compressor.5. The air conditioner according to claim 3, wherein the GHP outdoordevice includes: an outdoor heat exchanger control valve configured tocontrol a flow of the refrigerant flowing into the second outdoor heatexchanger; and a waste heat exchanger control valve configured tocontrol a flow of the refrigerant flowing into the waste heat exchanger.6. The air conditioner according to claim 5, wherein, when the EHPoutdoor device performs the defrosting operation, the controller closesthe outdoor heat exchanger control valve of the GHP outdoor device, andopens the waste heat exchanger control valve.
 7. The air conditioneraccording to claim 2, further including a temperature sensor provided onthe first outdoor heat exchanger and configured to detect a temperatureof the first outdoor heat exchanger.
 8. The air conditioner according toclaim 2, wherein the controller performs the defrosting operation of theEHP outdoor device at a predetermined frosting temperature difference,and switches the defrosting operation of the EHP outdoor device to awarming operation thereof at a predetermined defrosting completiontemperature.
 9. The air conditioner according to claim 8, wherein thepredetermined frosting temperature difference is a temperaturedifference between an external air temperature and a temperature of thefirst outdoor heat exchanger.
 10. The air conditioner according to claim8, wherein the predetermined defrosting completion temperature is atemperature at which the temperature of the first outdoor heat exchangeris about 10° C. or more.
 11. A method for controlling an air conditionerincluding at least one indoor device, an EHP outdoor device connected tothe at least one indoor device and configured to drive a firstcompressor using electric power, and a GHP outdoor device connected inparallel with the EHP outdoor device, connected to the at least oneindoor device and having an engine configured to drive a secondcompressor using a burned gas, the control method comprising: performinga warming operation of the EHP outdoor device and the GHP outdoordevice; switching the EHP outdoor device to perform a defrostingoperation when the EHP outdoor device reaches a predetermined frostingtemperature; and supplying a high pressure refrigerant from the GHPoutdoor device to the EHP outdoor device.
 12. The method according toclaim 11, wherein, in the supplying of the high pressure refrigerantfrom the GHP outdoor device to the EHP outdoor device, a two-stagecompression cycle in which the high pressure refrigerant from the GHPoutdoor device is compressed by the compressor of the GHP outdoor deviceand then compressed by the compressor of the EHP outdoor device isformed.
 13. The method according to claim 11, further includingswitching the EHP outdoor device to perform a warming operation when theEHP outdoor device reaches a predetermined defrosting completiontemperature.
 14. The method according to claim 11, wherein thepredetermined frosting temperature difference is a temperaturedifference between an external air temperature and a temperature of afirst outdoor heat.
 15. The method according to claim 13, wherein thepredetermined defrosting completion temperature is a temperature atwhich the temperature of the first outdoor heat exchanger is about 10°C. or more.
 16. The method according to claim 11, wherein the EHPoutdoor device includes a first four-way valve, which is switched to anEHP warming mode during which the first compressor is connected with theat least one indoor device when the EHP outdoor device performs thewarming operation, and which is switched to an EHP defrosting modeduring which the first compressor is connected with the secondcompressor of the GHP outdoor device when the EHP outdoor deviceperforms the defrosting operation.
 17. The method according to claim 16,wherein the GHP outdoor device includes: an outdoor heat exchangercontrol valve configured to control a flow of the refrigerant flowinginto the second outdoor heat exchanger; and a waste heat exchangercontrol valve configured to control a flow of the refrigerant flowinginto the waste heat exchanger.
 18. The method according to claim 17,further including closing the outdoor heat exchanger control valve, andopening the waste heat exchanger control valve when the EHP outdoordevice performs the defrosting operation.
 19. The method according toclaim 11, wherein the first outdoor heat exchanger includes atemperature sensor configured to detect a temperature of the firstoutdoor heat exchanger.
 20. An air conditioner, comprising: at least oneindoor device; an electric heat pump (EHP) outdoor device connected tothe at least one indoor device, configured to drive a first compressorusing electric power, and having a first outdoor heat exchanger thatperforms heat exchange with a refrigerant, and a first four-way valve; agas heat pump (GHP) outdoor device connected in parallel with the EHPoutdoor device, connected to the at least one indoor device, andincluding an engine configured to drive a second compressor using aburned gas, a second outdoor heat exchanger that performs heat exchangewith the refrigerant, and a waste heat exchanger configured to exchangeheat with the refrigerant using waste heat of the engine; and acontroller configured to control a warming operation or a defrostingoperation of the EHP outdoor device and the GHP outdoor device, and tosupply a high pressure refrigerant from the second compressor of the GHPoutdoor device to the EHP outdoor device while the EHP outdoor deviceperforms the defrosting operation by controlling the first four-wayvalve to supply the high pressure refrigerant from the second compressorto the first compressor, the first outdoor heat exchanger, and the wasteheat exchanger.
 21. The air conditioner according to claim 20, whereinthe controller switches the EHP outdoor device to perform the defrostingoperation when it is determined that the first outdoor heat exchanger ofthe EHP outdoor device is covered with frost while the EHP outdoordevice and the GHP outdoor device perform the warming operation.
 22. Theair conditioner according to claim 21, wherein the GHP outdoor deviceincludes: an outdoor heat exchanger control valve configured to controla flow of the refrigerant flowing into the second outdoor heatexchanger; and a waste heat exchanger control valve configured tocontrol a flow of the refrigerant flowing into the waste heat exchanger.23. The air conditioner according to claim 22, wherein, when the EHPoutdoor device performs the defrosting operation, the controller closesthe outdoor heat exchanger control valve of the GHP outdoor device, andopens the waste heat exchanger control valve.